A switchable cup tappet, also called a switching cup, is a device for adjusting or compensating valve lash in an internal combustion engine and can be switched to at least two different operational states for establishing different valve openings. In standard switching cups, the housing fulfils the function of transmitting the standard cam lift through the cylindrical bottom portion to the engine valve. Such tappet housings have to be secured against rotation.
In a switchable cup tappet known from DE-OS 43 14 619, a concentric reception bore is arranged at the center of the housing for receiving lift and force transmitting means which constitute the inner element and at the same time effect lash adjustment. In the case of this inner element, an inner housing arranged for axial displacement in the reception bore and an additional, separate cam permit the execution of a cam lift different from and, as a rule, smaller than the standard lift.
The inner element, or inner housing, can be displaced into and locked in different positions relative to the bottom. In a locked state, a higher lift is effected due to the action of the larger cam on the bottom portion. In the unlocked state, the smaller cam, which then acts directly on the inner element that is arranged for sliding in the reception bore, creates the lower lift of valve actuation.
In known switching cup housings, so-called eyes for the reception bores of the locking mechanism are made in one piece with the bottom and the inner guide. On the one hand, this increases the weight of the housing and, on the other hand, it necessitates complicated work procedures.